Millimeter wave bandpass filter using three-line microstrip structures

This paper presents a novel Ka-band millimeter bandpass filter rising three-line microstrip structures. A network analysis of a three-line unit is described, and the scattering parameters of the unit cell are derived. A demonstration three-line bandpass filter and a traditional two-line one, centered at 35 GHz, are designed, fabricated, and measured. The simulation and measured results are with good agreements. When compared with the conventional parallel coupled line inicrostrip structures, the new structure bandpass filter owns its practical advantages; it has improved stop band rejections, low insertion loss in pass band. reduced area of circuit layout, and released line spacing limitation for the first and last coupling units of filters. (c) 2006 Wiley Periodicals, Inc.